UDC (Universal Decimal Classification)

Classification system developed by the Belgian documentalists and lawyers Paul Otlet and Henri La Fontaine based on Dewey Decimal Classification, DDC (5.edition) and first published (in French) 1905-1907 by the Institut Internationale de Bibliographie.


In the beginning was the development of the DDC and the UDC coordinated and the idea was to establish one system with different editions for different sizes of collections. This idea was later given up (Miksa, 1998, p. 24+28).


UDC is the most detailed and specific of the general enumerative classification systems. but with pronounced facilities for synthesis. "The Medium Edition is some three times larger than that of the DDC (with greater powers of synthesis) and it is available in 21 languages" (Gilchrist, 1992, p. 69).


The system has in particular been applied in scientific and technological domains. In Denmark it is used by a number of libraries, including Aalborg University Library, Roskilde University Library (RUb), Royal School of Library and Information Science (RSLIS) and Technological Knowledge Center of Denmark (DTV). 


The publishing history of UDC is complex and presents "something of a bibliographical nightmare" (Rayward, 1975, p. 110, n. 58).


The maintenance of this classification has faced problems, for example, was FID dissolved 2002 and the Danish UDC organization was reorganized in 1992 and dissolved in 1999. Koch (1997) report problems in maintaining the system and writes:


"One of the main criticisms of the UDC is that the scheme is out of date. New knowledge is continually developing and existing knowledge is being redefined which causes problems for large schemes such as the UDC. Part of the problem of revisions to the scheme was also due to the unwieldy committee structure that was in place when the classification was under the control of the FID. . . .


Both SOSIG and NISS suggested that UDC was not updated frequently enough and that this caused problems. NISS commented that the main divisions of UDC (the top level) have their roots in the 19th century and are not intuitive to modern academics. SOSIG said they found two problems with currency: Firstly, some of the subjects seemed to be old-fashioned and outdated. For example, UDC has a section called 'feminism' which SOSIG users have suggested should be called 'gender studies'. Secondly, some subject areas seem to have 'out grown' their UDC section. The UDC hierarchy does not always grow at the speed required to keep up with subject areas that have developed significantly over recent years. For example, 'environmental issues' and 'development studies' are growing areas where there is a lot of interest and a lot of new resources, but these are not particularly well catered for by UDC". Koch (1997).








British Standards Institution (1993). Universal Decimal Classification. Standard Edition. London: British Standards Institution.


British Standards Institution (2005). Universal Decimal Classification. Standard Edition. Vol. 1-2. London: British Standards Institution. (Complete Edition, containing all available references and classifications). http://www.bsi-global.com/ICT/UDC/moreabout.xalter


Ducheyne, S. (2005). Paul Otlet's theory of knowledge and linguistic objectivism. Knowledge Organization, 32(3), 110-116. 


Gilchrist, A. (1992). UDC: the 1990s and Beyond. (pp. 69-77 IN: Williamson, N. J. & M. Hudon (eds.): Classification Research for Knowledge Representation and Organization. Amsterdam: Elsevier Science Publishers B. V. (FID 698).


Gilchrist, A. & Strachan, D. (Eds). (1990). The UDC: Essays for a New Decade. Aslib: London.


Lovitt, J. & Myers, G. (2003). An Examination and Comparison of the Dewey Decimal Classification and the Universal Decimal Classification Systems. http://web.archive.org/web/20050705070051/http://www.slais.ubc.ca/courses/libr517/02-03-wt2/projects/dewey/


Koch, T. (1997). The role of classification schemes in Internet resource description and discovery; work package 3 of Telematics for Research project DESIRE (RE 1004) www.ukoln.ac.uk/metadata/desire/classification


McIlwaine, I. C. (2000). The Universal Decimal Classification: guide to its use. The Hague: UDC Consortium. (UDC Publication, no P035).

McIlwaine, I. C. (2000). UDC in the twenty-first century. IN: The Future of Classification. Ed. by Rita Marcella and Arthur Maltby. Hampshire, England: Gower Publishing.


Miksa, F. (1998). The DDC, the Universe of Knowledge, and the Post-Modern Library. Albany, NY: Forest Press.


Rayward, W. B. (1975). The universe of information: The work of Paul Otlet for documentation and international organisation (FID 520). Moscow: FID.


UDK - en indføring. 1992.  Udarbejdet af Dansk Central for Dokumentation - DCD i samarbejde med Den danske UDK-komité.  Lyngby: Dansk Central for Dokumentation.


Williamson, N. J. (1992). Restructuring the UDC: Problems and Possibilities. (Pp. 381-387 IN: Williamson, N. J. & M. Hudson (Eds.): Classification for Knowledge Representation and Organization. Amsterdam: Elsevier Science Publishers B. V. (FID 698)



UDC Consortium: http://www.udcc.org/about.htm


UDC blog. http://universaldecimalclassification.blogspot.com/2007/10/library-and-information-science-in-udc.html





Birger Hjørland

Last edited: 19-10-2007